The present invention relates to a flexible conveyor belt which has a curved shape that elongates along a lower inner wall of a circular pipe, which runs while being supported above the lower inner wall by air introduced into a space between the belt and the lower inner wall, and which is mainly made of rubber or a resin.
A conveyor apparatus using such a flexible conveyor belt is called a pipe conveyor, and is employed for transporting general bulk goods such as sand, crushed stone, coal, or cement, or foods or grain such as wheat, soybean, or rice. An example of such a pipe conveyor will be described with reference to FIG. 7. Reference is made to Japanese Patent Publication (Kokai) No. Hei 4-317,911 for a pipe conveyor. In the pipe conveyor, an inner circular pipe 10 and an outer circular pipe 20 are disposed so as to constitute a coaxial double pipe, and a head pulley 30 and a tail pulley 40 are placed at the opposite ends of the inner and outer pipes 10 and 20, respectively.
A flexible conveyor belt 1 is extended between the pulleys 30 and 40. The forward belt 51 of the flexible conveyor belt 1 runs in a curved shape which elongates along the lower inner wall of the inner circular pipe 10, and the return belt 52 runs in a curved shape which elongates along the lower inner wall of the outer circular pipe 20. Seal members 60 are respectively attached to gap portions at both ends of the inner and outer pipes 10 and 20 and between the two pipes, excluding the portion through which the return belt 52 passes.
As shown in FIG. 8, an air duct 23 is attached to the lower portion of the outer circular pipe 20, and air blowing holes 22 through which air is guided from the air duct 23 to the lower inner wall of the outer circular pipe 20 are opened at regular intervals. A flange 89 is formed on a side face of the outer circular pipe 20. Air introduced into the space between the outer circular pipe 20 and the inner circular pipe 10 is guided to the lower inner wall of the inner circular pipe 10 through air blowing holes 12 which are opened at regular intervals in the inner circular pipe 10.
Returning to FIG. 7, an air blowing apparatus 80 is connected between the air duct 23 and the flange 89. In the apparatus 80, air pipes 83 and 84 are connected in parallel to the outlet of an air blower 82 having an air filter 81 disposed at the inlet, and the one air pipe 83 is connected to a flange 86 of the air duct 23 through a damper 85. Similarly, the other air pipe 84 is connected to the flange 89 through a damper 88.
In the above conveyor apparatus, goods to be conveyed M which are charged through a loading port 21 are transported on the forward belt 51 as shown in FIG. 8, and then drop from the head pulley 30 as shown in FIG. 7. The flexible conveyor belt runs while being supported by air above the lower inner walls of the respective circular pipes. Consequently, the conveyor apparatus has an advantage in that the power consumption for transportation and the noise level are much lower than those in a pneumatic conveyor, a roller conveyor, or a chain conveyor.
In the conveyor apparatus, the electric power required for transportation depends on the degree that the conveyor belt is raised by the air as the conveyor belt runs along the lower inner walls of the circular pipes. Therefore, it has been desired to develop a conveyor belt which can be surely supported by an air bearing along a circular pipe.